Typewriter erasing key



June 24, 1941. R. A. PRIMUS- TYPEWRITER ERASING KEY Filed Sept. 27, 1939 a dijllkEN TOR I c/iw awfzes ATTORNEY Patented June 24, 1941 rro STTES NT oFricE My invention relates to a special key usable with typewriters.

An object of my invention is to provide such a key which will erase typewritten letters.

A further object of my invention is to provide a key which is disassociated from the other typewriter keys and will function independently thereof.

A further object of my invention is to provide an erasing key which imparts an erasing motion across the letter to be erased, and in a vertical direction.

A further object of my invention is toprovide a unique mechanism which insures a positive abrasive motion against the letter when the device impacts against the letter.

A further object of my invention is to provide means for returning the abrasive member to normal position after impaction thereof.

A further object of my invention is to provide such a device which will in no way interfere with the balance of the typewriter mechanism and which can be made very small and yet accomplish the abrasive functions eificiently.

A further object of my invention is to provide the above mentioned objects in a construction of great simplicity and which can be manufactured at a reasonable cost.

With these and other objects in view, my invention consists in the construction, arrangement and combination of the various parts of my device, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claim, and illustrated in the accompanying drawing, in which:

Figure 1 is a side elevation showing the erasing key in inoperative as well as operative position,

Figure 2 is an enlarged detail taken in section of the erasing device,

Figure 3 i an end view of Figure 2,

Figure 4 is an enlarged detail showing the erasing device in operation substantially at the moment of impaction, and

Figure 5 is a slight modification showing the adjusting arrangement.

I have used the character it to designate generally the roller or platen of a standard typewriter which is attached to the rotatable shaft i l. The key of my device is indicated by the character l2 which key is pivoted in the usual manner about the haft l3. The shaft l3 extend through the other keys of the machine, but the key l2, however, is arranged to function independently of the other keys and does not work in combination with the other'devices which raise the typewriter ribbon etc.

The pull rod I4 is pivotally attached at IE to the projection iii of the hub ll in the usual. manner and the rod I4 is pivotallyattached at 18 to the customary lever 19 which is attached suitably through a system of further levers to the regular typewriter key which in this instance will bear the insignia such'as Eraser. The key I2 terminates in the portion 28 which extends into the further neck H, which neck is attached at 22 to the substantially U-shaped channel 23. Pivotally attached within the channel 23 at 24 are the two extending members 25 and 26 which extend outwardly from the member 23 and which members in turn are pivoted at 27 to the further channel member 28 which channel member extends into a further outwardly disposed channel 29. The channel 29 receives the eraser or abrasive member 39 which member is necessarily rectangular in shape and is received within the channel 29.

The eraser can be made of any suitable hape for the purpose intended with a metallic base if desired. It must be of the necessary quality to provide a good abrasive surface. The members 25 and 26 include square shoulders at 3| (see Figure 2). The square shoulders 3| are cut at such an angle to limit the outward movement of the members 25 and 26 so that they Will constantly maintain the angular position as shown in Figure 2 in inoperative position. It will be noted that the other shoulders adjacent the pivoting points are rounded so that the members 25 and 26 can readily collapse. A spring member 32 is firmly attached at 33 to the member 26 and at 34 to the channel 23.

Now that the essential features of the invention have been explained I shall explain the operations thereof. Assuming that the paper which is being written upon is indicated by the character 35 (see Figure 1) which paper naturally surrounds the platen I0, it will be seen that by operation of the erasing key that the key I2 is brought to the vertical position as shown by the dotted structure. Since the key l2 functions independently of the other keys in the machine there is no danger of its contacting the ribbon or any of the other movable parts. The sharp impact caused by the operation of the erasing key causes the erasing surface 36 to strike against the paper as shown, which in this case will be the letter to be erased. At the moment of impact, since the collapsible arrangement is moving directly towards the platen, the tendency will be for the eraser member 30 to be moved directly downwardly in a positive and rapid manner.

During this action the members 25 and 26 pivot upon their respective pivots and against the tension of the spring 32. This action is shown clearly in Figure 4 showing the position of the eraser slightly after the moment of impact which eraser of course can travel downwardly to a still further distance and if necessary can travel in this manner until the channels 23 and 28 abut. The dotted portion at Figure 4 shows the position the eraser takes at the beginning of the motion. This firm action which takes place exactly at the moment of impact results in a sharp abrasive action exerted downwardly and directly against the letter to be erased thereby removing the letter itself.

The key can be struck two or three times if necessary to completely remove the letter which operations of course can be performed very quickly. After impact, the structure returns to the position shown in Figures 1 and 2. The angle of the members 25 and 26 insures that the compressive action is made positive and starts the initial action in a moreeificient manner which may not be true if the members 25 and 26 were positioned directly at right angles to the further channel members. It will be noted particularly through the above description that there is no necessity for cumbersome levers and the like since the device operates automatically upon impact only and derives its eflicient features from the fact that the downward movement of the erasing member is caused only by the action of the striking portion of the device itself and in this manner the device functions positively which would not be true with an arrangement of cumbersome levers and the like which would require special attention and which would not be as efficient as the action shown herein.

The Figures 2 to 5 inclusive are necessarily made larger than the actual size of the device in order to show the action of the device more clearly, and the approximate size is that of Figure l which is also made larger and the resulting device can be made very small, having a great amount of efficiency. The erasing members 30 can be replaceable.

Figure 5 illustrates a slight modification with the same features being used with the exception that the adjusting tongue 36 is received within a slot 31 and a small lock screw 38 is used to lock the members in fixed position. This structure can be used if it is desired to provide means for vertical adjustment. It will be noted that the angle and the size of the members can be changed to suit any requirements and that the extent of travel of the erasing member can be limited to only that amount necesary. It will now be seen that I have provided a typewriter erasing key which will erase typewritten letters, which is independently operable from the other keys of the typewriter, which includes an erasing member which will impart a vertical abrasive motion across the letter to be erased, which eliminates the necessity of additional levers etc., which functions at the moment of impact only and in a positive manner, which can be made small and of a neat structure, and which can be manufactured at a very reasonable cost.

Some changes may be made in the construction and arrangement of the parts of my invention without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claim any modified forms of structure or use of mechanical equivalents, which may be reasonably included within its scope.

I claim as my invention:

A typewriter erasing key comprising a pivoted lever, a bar attached at the end of said pivoted lever and substantially parallel thereto, a further bar including an erasing member parallel to said bar, a pair of arms of equal length pivoted to said bar and. said further bar to maintain said bar and said further bar in constant parallel relationship, said arms'being of equal length and said parallel bars providing a parallelogram whereby said further eraser bearing bar is moved in a constant vertical plane upon impaction of said eraser with a typewritten sheet.

RALPH A. PRIMUS. 

